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Fast food for walruses

The main food source for the Atlantic walrus is molluscs, which live in the sediments, at the bottom of the ocean. It's for this very reason that the walruses prefer to live near shallow waters. It's a shorter trip to the dinner table.

When it's time to eat, walruses swim to the bottom of the ocean and dig up the molluscs from the shallow ocean floor. They also feed on fish and other invertebrates that live on or near the bottom of the ocean.

This species has been identified as Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). It is currently being considered for listing under the federal Species at Risk Act (SARA). Protection is afforded through the federal Fisheries Act. If listed under the SARA, it will be afforded additional protection. Under the SARA, a management plan must be developed for this species.

General Description

The Atlantic Walrus (Odobenus rosmarus rosmarus) is a large, sociable marine mammal. It is one of two subspecies that are still in existence; the other is the Pacific Walrus (O. r. divergens). Together they are the only living representatives of the family Odobenidae. Some common names include Aivik (Inuktitut), Morzh (Russian), Rostungur (Icelandic), and Valross (Swedish). It has the following characteristics:

Large body with limbs that have developed into flippers;

Front flippers support the body in an upright position;

Hind flippers similar to seal hind flippers;

Skin is between two and four cm thick;

Upper canine teeth develop into long tusks; longer and broader in males than females;

Moustache made of quill-like whiskers;

Hair on newborns is silver grey; sparse adult hair;

Cinnamon brown in colour; may appear pink on a warm day or white after a lengthy dive;

Newborns weigh about 55 kg and are 1.2 m long; and

Adult males reach up to 1,100 kg in weight and 3.1 m in length; females 800 kg and 2.8 m

Distribution

The global range of the Atlantic Walrus includes the central Canadian Arctic to the Kara Sea in the east, Svalbard in the north, and Nova Scotia in the south. Two distinct populations, one east and one west of Greenland, exist within this range.

In Canada, the Atlantic Walrus occurs from Bathurst and Prince of Wales islands to Davis Strait, and from James Bay north to Kane Basin.

Four distinct Canadian populations still exist:

South and East Hudson Bay,

Northern Hudson Bay - Davis Strait,

Foxe Basin,

and Baffin Bay (High Arctic)

A fifth Maritime population is considered extirpated.

Habitat and Life History

The habitat requirements of the Atlantic Walrus are very specific. They need large areas of shallow, open water (80 m or less), which support an abundant clam community. In addition, there must be ice or land nearby to ‘haul out’. Moving pack ice is ideal for this purpose; however, in the summer and fall when ice is scarce, large herds congregate and haul out at uglit, which are often located on low, rocky shores with steep subtidal zones. Mating occurs from February to April. Little is known about their reproduction because they mate in the water and in remote areas. Males mature between 7 and 13 years of age. They compete for females and may even defend access to them for up to five days. Females mature between 5 and 10 years of age and give birth on average every three years. Gestation lasts about 11 months and the young nurse for up to 27 months. Protective care by mothers and the herd assures high calf survival.

Diet

The preferred food item is bottom-dwelling organisms such as clams and sea urchins. Walruses likely identify prey in the bottom sediments with their whiskers and unearth them with the snout. They suck clams out of their shells by creating a vacuum with their tongues. Walruses are also known to occasionally eat fish and some adults have been found with pieces of seal or whale skin and fat in their stomachs. Walruses less than three years old consume mostly milk.

Threats

The Maritime population was heavily hunted, especially in the 17th and 18th centuries, and by the end of the 18th century had been extirpated. Hunting is also the most important current threat to the four populations that still exist. In addition, human activities that create noise and disturbance may cause walruses to abandon uglit or stampede, resulting in calf mortalities and spontaneous abortions. By comparison, however, this and other threats such as contaminants, climate change and industrial development, are minor to the impacts of hunting.

Similar Species

There are no similar species. The Pacific Walrus, a subspecies, is heavier with longer tusks and a wider head.